0. Table of contents
Last Updated 15 Sep 2020
1. Timing Calibrations of X-ray missions
1.1 Summary of Timing Requirement and Calibrations
| Mission/Instruments | Science Requirement Absolute Time | Timing System Design | Timing Calibration Status | In-orbit Timing Calibration Targets | Reported Issues | Reference | ||
|---|---|---|---|---|---|---|---|---|
| Requirement | Goal | GPS Receiver | Clock Stability | (Absolute Timing Precision) | ||||
RXTE/PCA  | ||||||||
| Chandra / ACIS | 0.25625 s (one minor frame start time) | 0.001 s (synchronize minor frame starts) | No (sync DSN) | 3.2 μsec | 285 ± 6 μsec | None at present | Davis et al. 2003 (davis.pdf) | |
| Chandra / HRC | 16 μsec | 4 ± 4 μsec | Crab PSR B1821-24 | Time tag gets attached to next event; correctable under special mode for HRC-S which telemeters all events and then reassigns times on the ground | Davis et al. 2003 (CXOClock.pdf) | |||
| XMM-Newton/EPIC-MOS | ||||||||
| XMM-Newtion/EPIC-PN | 1 ms | none | No | - | 108 μsec | Crab pulsar (bi-annual) | None currently | Kirsch et al, SPIE, 5165, 85 Martin-Carrillo et al, A&A, 545, A126 (2012) |
| INTEGRAL/SPI | ||||||||
| INTEGRAL/IBIS | ||||||||
| Swift/BAT | ~ 0.3 ms | GRB light curves | Yes | ~ 6.572 x 10^-8 s/s | ~ 100 us (with offset of ~ 80 us) | Crab pulsar (anual) | None at present | BAT team wiki page; private communication with Michael Tripicco see BAT Wiki: Pre-launch Timing, BAT Wiki (410.4-SPEC-0005F.pdf) (Limited Access) |
| Swift/XRT | ~ 10 ms | ~ 270 us | Crab pulsar | None at present | G. Cusumano et al 2012 D. Burrows et al. 2005 | |||
Suzaku/XIS | No science requirement defined. | No | 1.9 x 10^-9 s/s | Not confirmed. | A0535+262, Her X-1, etc | N/A | Y.Terada et al 2008 (10.1093/pasj/60.sp1.S25) | |
| Suzaku/HXD | 360±150 μsec (270±130 μsec in condition) | Crab for coordinated PSR1509-58 | Timing shift by a failure in time stamp at the ground station during 2012-2014 (Shu Koyama, Fixed) | |||||
| NuSTAR/FPM | Should be 100 ms | none | No | Freely drifting by ~3 ms/day. | 65 us (1-sigma) | Crab | ~5ms offset using Corrected through | Bachetti+ in prep (can distribute early copy) |
| AstroSat/LAXPC | None defined | Yes (offline referral) | 4 μsec rms after GPS synchronization | fixed offset | Crab Pulsar (with Radio) | None at present | D. Bhattacharya 2017 (10.1007/s12036-017-9461-x) Basu et al (in prep) | |
| AstroSat/CZTI | None defined | Yes (offline referral) | 3 μsec rms after GPS synchronization | fixed offset -650 ±70µs w.r.t. Fermi-LAT | Crab Pulsar GRBs | None at present | D. Bhattacharya 2017 (10.1007/s12036-017-9461-x) Basu et al 2018 Basu et al (in prep) | |
| HXMT | ||||||||
| Hitomi/SXS, SXI, HXI, SGD | 350 μsec | 35 μsec | Yes | 0.01μsec(GPSR) | ~ 120-230 μsec | Crab (with radio) note: using out-of-time event for SXI | absolute timing accuracy is much larger than expected on ground (3 μsec) | Y.Terada et al 2018 (10.1117/1.JATIS.4.1.011206) |
| NICER | 100 ns (RMS) | none | Yes | N/A | Approx. 3 µs | Crab Pulsar PSR B1821-24A PSR B1937+21 | Precise 1-second offset in on-board timestamps due to flight software bug; corrected using TIMEZERO keyword in pipeline-processed FITS data files. (see HEASARC page for detail) | Markwardt et al. (in prep.) |
| eROSITA | ||||||||
XRISM/Resolve  | 1 msec | none | Yes | same as Hitomi | (under discussion) | |||
| XRISM/Xtend | 10 msec | none | Yes | (under discussion) | ||||
Mission completed.
Future Mission
1.2 Point of Contacts
| Mission | PoC |
|---|---|
| RXTE | to be confirmed |
| Chandra | Vinay Kashyap |
| XMM-Newton | Felix Fuerst, Simon Rosen |
| Swift | Amy Lien |
| INTEGRAL | Guillaume Belanger, Volodymyr SAVCHENKO |
| NuSTAR | Matteo Bachetti, Katja Pottschmidt |
| Astrosat | Gulab Dewangan, Dipankar Bhattacharya |
| HXMT | Xiaobo LI |
| NICER | Craig Markwardt, Teruaki Enoto |
| eROSITA | to be confirmed |
| Suzaku | Yukikatsu Terada |
| Hitomomi | Yukikatsu Terada |
| XRISM | Yukikatsu Terada |
2. In-orbit Timing Calibration Plan/Observations
2.1 Archive Data
2.1.1 List of Coordinated Observations useful for Timing
2.1.2 Reports
2.2 New Coordinated Observations
3. Studies on Timing
3.1 effects on timing products (power spec, light curve etc) by the detector’s behavior (dead time, grade selection of calorimeter etc)
4. Timing Tools, (with Statistic Group)
5. Notes